JPH0792687B2 - Adjuster - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to an adjusting device for performing a PID adjusting operation, and in particular, in order to effectively utilize the characteristic of a measured value differential preceding PID, a control amount The present invention relates to an adjusting device adapted to give the differential operation output of the above to the deviation.

(Prior Art) Conventionally, PID control devices have been widely used in all industrial fields. At present, the digital arithmetic control method is widely used instead of the analog arithmetic control method, which is indispensable for plant control.

The basic operation formula of such PID control is MV (s) = Kp {(1+ (1 / T _I · s) + (T _D · s) / (1 + η · T _D · s)} · E (s) …
It is represented by (1). However, MV (s) is an operation signal, E (s) is a deviation, Kp is a proportional gain, T ₁ is an integration time, T _D is a differentiation time, s
Is a Laplace operator, η is a coefficient, and (1 / η) is a differential gain. This arithmetic expression is for performing PID calculation on the deviation E, and is usually called deviation PID control.

However, in the case of this PID control, the target value SV often changes in a stepwise manner, and the D (differential) operation acts excessively with respect to this change in the target value SV, causing a sudden change in the operation signal MV. There is a problem in that the controlled object is impacted or the target value following characteristic largely overshoots to cause a vibration phenomenon.

Therefore, in recent years, “measured value differential preceding PID control”, which executes the D operation for the controlled variable PV instead of the deviation, has come to be used.

The calculation formula of this measured value differential preceding PID control is MV (s) = Kp [{1 + 1 / (T _I · s)} · E (s) − {(T _D · s) / (1 + η · T _D · s)} ・ PV (S)]…
It is represented by (2). PV (s) is the controlled variable from the controlled object.

FIG. 5 is a block diagram of a conventional adjusting device to which the measured value differential preceding PID control system is applied. In this device, after the deviation E between the target value SV and the controlled variable PV from the controlled object 2 is obtained by the deviation calculation means 1, this deviation E is introduced into the PI adjustment calculation means 3, where (2) PI adjustment calculation is performed according to the calculation formula shown on the front side of the formula, and the obtained PI adjustment calculation output is introduced into the subtraction unit 4.

Further, the control amount PV from the controlled object 2 is the differential adjustment calculation means 5
In this case, the incomplete differential calculation is performed according to the calculation formula shown in the latter part of the formula (2), and the obtained incomplete differential calculation output MV _D is introduced into the subtracting means 4. Then, the subtraction means 4 subtracts the incomplete differential calculation output from the PI adjustment calculation output, and the obtained signal is guided to the addition means 6 as the operation signal MV, where it is added and synthesized with the disturbance signal D to be controlled. By applying it to 2, control is performed so that the target value SV ₀ = the control amount PV.

(Problems to be Solved by the Invention) However, although the adjusting device to which the measured value differential leading PID control system is applied has various features, on the other hand, it has the following defects. .

First, the adjusting device to which the measured value differential preceding PID control system is applied cannot sufficiently cope with the configuration of FIG. 5 due to the characteristics of the controlled object 2, and it is necessary to perform various kinds of processing to obtain operation signals. . FIG. 6 is a diagram showing one example of processing, in which a non-linear means 7 is provided on the output side of the deviation calculation means 1 and the deviation E obtained by the deviation calculation means 1 is processed by the non-linear means 7 for example dead zone processing. After the non-linear processing such as the deviation square processing and the gap processing, the PI adjustment calculation means 3 is introduced.

As described above, in actual plant control, non-linear processing is frequently used for the deviation E in order to deal with various characteristics of the controlled object 2, but the differential adjustment calculation output MV _D is the output of the PI adjustment calculation means 3. Since it is bypassed to the side, the differential characteristic is not subject to nonlinear processing, and therefore accurate nonlinear processing cannot be performed, and the differential adjustment operation output MV _D bypasses and adversely affects the control system, reducing controllability. Is causing

Also, this measured value differential preceding PID adjusting device is a one-degree-of-freedom PID adjusting device in which only one set of PID parameters can be set. As a result, since the proportional gain and the derivative time have one degree of freedom, there is a problem that optimal control that satisfies both the disturbance suppression characteristic and the target value tracking characteristic cannot be performed.

Therefore, as long as the above defects exist, the PID control function cannot be sufficiently exerted on various control targets. In particular,
In the future, plant operation control will be required to have higher precision, faster response, optimization, and perfection, but in order to sufficiently meet these requirements, the PI that is widely used in plants.
It is necessary to immediately remove the above defects of D control.

The present invention has been made under the above-mentioned demands, and various non-linear processes such as a dead zone, a deviation square, a gap, etc. can be accurately performed including a differential operation, and a proportional gain and a differential time of 2 can be obtained. It is an object of the present invention to provide an adjusting device that can easily realize a degree of freedom.

[Structure of the Invention] (Means for Solving the Problems) First, in order to solve the above problems, the invention corresponding to claim 1 is based on a deviation between a target value and a controlled variable of a controlled object.
In an adjusting device that performs an adjustment operation to obtain an operation signal to be applied to the controlled object, a differential adjustment operation means that performs a differential adjustment operation based on the control amount, and a differential adjustment operation means based on a target value setting signal or the deviation. A means for subtracting the output or adding the output of the differential adjustment calculation means to the control amount is provided.

Further, the invention according to claim 2 is the invention according to claim 1, further comprising advance / delay calculation means for advancing or delaying the target value setting signal, and the output of this advance / delay calculation means is used to obtain the above-mentioned information. By subtracting the output of the differential adjustment calculation means to obtain the target value, the two-degree-of-freedom control is performed only for the P motion.

Further, the invention according to claim 3 is the invention according to claim 2, further comprising coefficient multiplying means for multiplying the target value setting signal by a coefficient, and the deviation between the output of the coefficient multiplying means and the control amount is calculated. P + is obtained by performing the differential adjustment calculation by the differential adjustment calculation means and subtracting the output of the differential adjustment calculation means from the output of the lead / lag calculation means to obtain the target value.
This is a configuration for performing D two-degree-of-freedom control.

(Operation) Therefore, according to the invention of claim 1, since the differential adjustment calculation means obtains the differential adjustment calculation output from the controlled variable of the controlled object by taking the above-mentioned means, the differential adjustment is performed from the target value setting signal. Whether to obtain the target value of the PI adjustment calculation means by subtracting the adjustment calculation output, or after subtracting the differential adjustment calculation output from the deviation between the target value and the control amount, and then supplying it to the PI adjustment calculation means,
Alternatively, by adding the differential adjustment calculation output to the control amount and supplying it to the deviation calculating means, it is possible to perform various modification processes on the deviation including the differential operation and execute the desired modified PID control.

Further, the invention of claims 2 and 3 advances to the target value setting signal /
A target value filter having a delay calculation function is provided to have the same operation as that of claim 1, and the proportional gain and the integration time of 2
A degree of freedom can be realized.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIG. In the figure, 11 is the controlled variable PV from the controlled object 12.
Regarding the measured value differential derivative calculation means for performing differential adjustment calculation in order to take advantage of the advantage of the preceding type, 13 is the target value setting signal S
The target value SV is obtained by subtracting the output of the differential adjustment calculation means 11 from V '.
Subtraction means for obtaining the deviation, 14 is a deviation calculation means for calculating the deviation by subtracting the control amount PV from the target value SV obtained by the subtraction means 13,
Reference numeral 15 is PI adjustment calculation means, and 16 is addition means for adding the disturbance D to the operation signal MV output from the PI adjustment calculation means 15 and applying it to the controlled object 12.

Next, the operation of the above apparatus will be described. The present apparatus is to effectively process the deviation E and the like and execute the PID control while taking advantage of the measured value differential leading type.

Therefore, first, the state of involvement of the differential adjustment calculation means 5 in the control system in the conventional apparatus (FIG. 5) will be considered, and then the state of involvement of the differential component in the apparatus of the present invention will be compared.

That is, the differential component MV _D of the operation signal MV obtained by passing the controlled variable PV of the controlled object 2 through the differential adjustment calculation means 5 in the conventional device is MV _D (s) = {(T _D s) / (1 + η ・T _D・ s)} ・ PV (s)…
It is represented by (3). Here, when the controlled variable PV (s) changes stepwise with the magnitude of a, that is, when PV (s) = a / s, the initial value of the differential component MV _D (s) in the time domain is mv _D ( 0) and the final value is mv _D (∞), from the final value theorem, And from the initial value theorem, Is obtained.

Next, consider the first embodiment of the device of the present invention. Now, when the prior art device as well as controlled variable PV (s) is a step change in the size of a, that is PV (s) when = a / s, the differential component of the operation signal _{^{MV ▲ MV 'D ▼ (s}} ) The initial value in the time domain is ▲ mv ^′ _D ▼ (0), and the final value is ▲ mv ^′
_{If D} ▼ (∞), from the theorem of the final value, And from the initial value theorem, Is obtained.

Here, equations (4) and (6) are used between the initial values and the final values of the differential components in the conventional device and the device of the present invention.
From equations (5) and (7), mv _D (0) = ▲ mv ^′ _D ▼ (0) = Kp · (a / η) (8) mv _D (∞) = 0 ≠ ▲ mv ^′ _D ▼ (∞) = Kp · a · (T _D / T _I ) ... (9) That is, as is apparent from the equations (8) and (9), between the conventional device and the device of the present invention,
The initial values of the differential component in the time domain are equal, but the final values in the time domain are not.

Therefore, the final value mv in the time domain of the equation (7) of the device of the present invention
We need to prove that _D (∞) is based on the differential action. Then, in order to prove that the configuration of the device of the present invention is the differential operation, the differential operation in the interference type PID control of FIG. 7 which is used as the optimum one for the conventional actual control will be analyzed. . FIG. 7 shows a configuration in which a lead / lag calculating means 8 is inserted between the deviation calculating means 1 and the PI adjusting calculating means 3, and the operation signal M at this time is inputted.
The differential component of V ″ is Becomes That is, in the device of FIG. 7, the controlled variable PV
When (s) changes stepwise with the size of a, that is, PV
When (s) = a / s, the differential formation of the operation signal MV ″ ▲ MV ^″ _D ▼
Given that the initial value ▲ mv ^″ _D ▼ (0) and the final value ▲ mv ^″ _D ▼ (∞) in the time domain of (s) are And from the theorem of initial values, Is obtained. Here, since η = 0.1 can be set,
From equations (7) and (12), ▲ mv ^′ _D ▼ (∞) = Kp · a ・ (T _D / T _I ) ▲ mv ^″ _D ▼
(∞) = Kp · a · (T _D / T _I ) 0.9, which is equivalent to the differential component of FIG. 7, which is the most practical control. That is, it can be proved that the device having the configuration shown in FIG. 1 is equivalent to the conventional PID control shown in FIG.

Therefore, the device of the present invention eliminates the bypass component due to differentiation, and even if the deviation E is processed and various modifications such as non-linear processing are performed, the modification processing including the differential operation can be accurately performed, and thus the desired modification. PID control can be executed.

Although the control amount PV is differentially adjusted and subtracted from the target value setting signal SV 'in the above embodiment, the differential adjustment calculation output may be subtracted from the deviation E, or as shown in FIG. As described above, the deviation E may be obtained by adding the output of the differential adjustment calculation means 11 to the control amount PV by the addition means 17 and subtracting the output of the addition means 17 from the target value SV.

Next, FIG. 3 is a configuration diagram showing a second embodiment of the present invention. This apparatus is provided with a target value filter for the target value setting signal SV ', that is, a lead / lag calculating means 21, and a subtracting means 13 on the output side of the lead / lag calculating means 21, where the lead / lag calculating means is provided. From the output of the means 21, the differential adjustment calculation means 11
The configuration in which the output of is subtracted to obtain the target value SV is added.

The response formula of the controlled variable PV in the device of FIG. 3 is It is represented by. Here, the target value tracking optimal algorithm is C
^* (S) can be expressed by the following arithmetic expression.

C ^* (s) = F (s) C (s) = Kp {α + (1 / T _I · s)} (14) where C (s) = Kp {(1+ (1 / T _I · s) )} Therefore, if the target value filter F (s), which is the advance / delay calculation means 21, is calculated based on this equation (14), Therefore, from this equation (15), it has a lead / lag calculation function with a differential action. Therefore, this device is
Besides having the same function as in the figure, the proportional gain of the disturbance suppression optimal control is Kp, while the proportional gain of the target value tracking optimal control is α · Kp. By varying this α, only P motion has two degrees of freedom. Can be realized.

Furthermore, FIG. 4 is a block diagram showing a third embodiment of the present invention. This device comprises a coefficient multiplying means 31 for multiplying the target setting signal SV by a coefficient γ, a subtracting means 32 for subtracting the output of the coefficient multiplying means 31 from the control amount PV, and a differentiation for differentially calculating the output of the subtracting means 32. The adjustment calculation means 11 is provided and the target value SV is obtained by subtracting the output of the differential adjustment calculation means 11 from the output of the lead / lag calculation means 21.

The response formula of the controlled variable PV in the device shown in FIG. It is represented by. Here, the target value tracking optimal algorithm is C
^{Assuming that} (s), this C ^** (s) can be expressed by the following arithmetic expression.

And if this equation (17) is transformed, Can be obtained. Here, using the relation of equation (14), Therefore, K (s) = (T _D · s) / (1 + η · T _D · s) and C (s) = Kp {1+ (1 / T _I · s)}, so (19) From the formula, R (s) = γ is obtained. That is, the coefficient R (s) of the coefficient multiplication means 31 becomes γ.

Therefore, according to the configuration of this embodiment, the proportional gain of the disturbance suppression optimal control is Kp, and the differential operation is On the other hand, the proportional gain of the target value tracking optimum control is α ・
It becomes Kp, and the differential action at that time is Therefore, by varying the coefficient α of the target value filter and the coefficient γ of the coefficient multiplying means 31, it is possible to realize the two-degree-of-freedom optimum control of the P + D operation.

[Effects of the Invention] Therefore, as described above, according to the present invention, the following various effects are achieved.

First, in claim 1, the deviation can be variously deformed including the differential operation, and thus the desired PI can be deformed.
It is possible to provide an adjusting device capable of executing D control.

Next, in the second aspect, the deviation can be variously modified including the differential operation, and the two degrees of freedom of only the P operation can be easily controlled.

Further, according to the third aspect, the deviation can be variously modified including the differential operation, and the two degrees of freedom of the P + D operation can be easily controlled.

[Brief description of drawings]

FIG. 1 is a block diagram showing the first embodiment of the device of the present invention, FIG. 2 is a diagram showing a modification of FIG. 1, and FIGS. 3 and 4 are other embodiments of the device of the present invention. FIG. 5 is a block diagram showing an example, and FIGS. 5 to 7 are block diagrams showing the configuration of a conventional device. 11: differential adjustment calculation means, 12: controlled object, 13: subtraction means, 14: deviation calculation means, 15: PI adjustment calculation means, 16
...... Adding means, 17 ...... Adding means, 21 ...... Advancing / lagging calculating means (target value filter), 31 ...... Coefficient multiplying means.

Claims (3)

[Claims] 1. An adjusting device for obtaining an operation signal to be applied to the controlled object by performing a P (proportional) I (integral) adjustment calculation based on a deviation between a target value and a controlled variable of the controlled object. And a means for subtracting the output of the differential adjustment computing means from the target value setting signal or the deviation, or for adding the output of the differential adjustment computing means to the control amount. An adjusting device comprising: PID control including D (differential). 2. An adjusting device for performing a PI adjustment operation based on a deviation between a target value and a controlled variable of a controlled object to obtain an operation signal to be applied to the controlled object, wherein a differential adjustment operation is performed based on the controlled variable. Derivative adjustment calculation means, advance / delay calculation means for advancing or delaying the target value setting signal, and target value for obtaining the target value by subtracting the output of the differential adjustment calculation means from the output of this advance / delay calculation means. An adjusting device, comprising: a setting means, wherein the P motion has two degrees of freedom. 3. An adjusting device for obtaining an operation signal to be applied to the controlled object by performing a PI adjustment calculation based on a deviation between a target value and a controlled variable of the controlled object, and advancing or delaying the target value setting signal. / Delay calculation means, coefficient multiplication means for multiplying the target value setting signal by a predetermined coefficient, subtraction means for subtracting the output of the coefficient multiplication means from the control amount, and differential adjustment based on the output of the subtraction means And a target value setting unit for subtracting the output of the differential adjustment calculation unit from the output of the lead / delay calculation unit to obtain the target value.
An adjusting device having two degrees of freedom for P movement and D movement.